Speculation and Risk in Foreign Exchange Markets

Speculation and Risk in Foreign Exchange Markets

Chapter 7 Speculation and Risk in the Foreign Exchange Market © 2018 Cambridge University Press 7-1 7.1 Speculating in the Foreign Exchange Market • Uncovered foreign money market investments • Kevin Anthony, a portfolio manager, is considering several ways to invest $10M for 1 year • The data are as follows: • USD interest rate: 8.0% p.a.; GBP interest rate: 12.0% p.a.; Spot: $1.60/£ • Remember that if Kevin invests in the USD-denominated asset at 8%, after 1 year he will have × 1.08 = $10. • What if Kevin invests his $10M in the pound money market, but decides not to hedge the foreign$10 exchange risk?8 © 2018 Cambridge University Press 7-2 7.1 Speculating in the Foreign Exchange Market • As before, we can calculate his dollar return in three steps: • Convert dollars into pounds in the spot market • The $10M will buy /($1.60/£) = £6. at the current spot exchange rate • This is Kevin’s pound principal. $10 25 • Calculate pound-denominated interest plus principal • Kevin can invest his pound principal at 12% yielding a return in 1 year of £6. × 1.12 = £7 • Sell the pound principal plus interest at the spot exchange rate in 1 year 25 • 1 = × ( + 1, $/£) ( + 1) = ( + 1) × ( / ) – (1 + 0.08) • £7 £7 $10 © 2018 Cambridge University Press 7-3 Return and Excess Return in Foreign Market • We can use the previous calculation to deduce a formula for calculating the return in the foreign market, 1 rt( +=1) ×+( 1it( ,£)) × St( + 1) St( ) • The return on the British investment is uncertain because of exchange rate uncertainty. • The excess return is the difference between the risky investment and the riskless investment in dollar deposits: St( +1) exr( t +=1) ×+( 1,£1,$i( t)) −+( i( t )) St( ) © 2018 Cambridge University Press 7-4 7.1 Speculating in the Foreign Exchange Market • Speculating with forward contracts [ $ ] = × +=BE • Break-even spot rate: [ £ ]. The excess return is zero if St( 1) S 1+ • Kevin’s breakeven rate would be: 1+ • = $1.60/£ × (1 + 0.08)/(1 + 0.12) = $1.5429/£ • If future exchange rate < forward: negative excess return • If future exchange rate > forward: positive excess return • Comparing forward market and foreign money market investments • ( $) = ( + 1) = [ ( + 1) – ( )]/ ( ) • ( + 1) × [1 + (£)] = [ ( + 1)/ ( )] × [1 + (£)] [1 + ($)] • That is, the forward market return is simply the excess return when interest parity holds − © 2018 Cambridge University Press 7-5 7.1 Speculating in the Foreign Exchange Market • Currency speculation and profits and losses • Quantifying expected losses and profits • Use the conditional expectation of the future exchange rate • Kevin expects the £ to depreciate against the $ by 3.57% over next year • $1.60/£ × (1 0.0357) = $1.5429/£ • £ × $1.5429/£ = $10. − • At what forex rate will Kevin just get his $10M back? 7 8003 • £ × = = $1.4286/£ • Probability that he will lose with 10% standard deviation of appreciation of £ would be [ ( + 1, $/£) $1.54297/£]/($0.$1016/£) • = [$1.4286/£ $1.5429/£]/($0.16/£) = 0.7144 − • This works out to 23.75% probability that ( + 1/$/£) < $1.4286/£ − − © 2018 Cambridge University Press 7-6 Probability Kevin is a Loser • Kevin finds the standard deviation of the change in the exchange rate is 10%. The current spot rate is $1.60, so one standard deviation is $0.16 • Since the exchange rate change has a normal distribution, if we divide the change by the standard deviation, we have a “standard Normal”, N(0,1) distribution. • Here we want the probability that [$1.4286/£ $1.5429/£]/($0.16/£) will occur, or worse • = [$1.4286/£ $1.5429/£]/($0.16−/£) = 0.7144 • This works out to 23.75% probability that ( + 1/$/£) < $1.4286/£ − − © 2018 Cambridge University Press 7-7 Exhibit 7.2 Standard Normal Distribution © 2018 Cambridge University Press 7-8 7.2 Uncovered Interest Rate Parity and the Unbiasedness Hypothesis • Covered interest rate parity • Doesn’t matter where you invest – you’ll have the same domestic currency return as long as the foreign exchange risk is covered using a forward contract • Uncovered interest rate parity • Domestic and foreign investments have same expected returns • In the context of Kevin’s investment, suggests that the pound is not a great investment relative to the dollar – in fact, it suggests that the pound will depreciate by 3.57% • Unbiasedness hypothesis • No systematic difference between the forward rate and the expected future spot rate © 2018 Cambridge University Press 7-9 7.2 Uncovered Interest Rate Parity and the Unbiasedness Hypothesis ( + 1) ( ) 1 + (£) = 1 + ($) = 1 + (£) ( ) ( ) Uncovered Interest Covered Interest Rate Parity Rate Parity ESt ( t+=1) F( t) © 2018 Cambridge University Press 7-10 7.2 Uncovered Interest Rate Parity and the Unbiasedness Hypothesis • Forecast error • The difference between the actual future spot exchange rate and its forecast St( +−11) EStt ( +) • Unbiased predictors • Implies expected forecast error = 0 • Can have large errors as long as not favoring one side © 2018 Cambridge University Press 7-11 7.2 Uncovered Interest Rate Parity and the Unbiasedness Hypothesis • The unbiasedness hypothesis and market efficiency • If the forward rate were biased then one side or the other of a bet (i.e., futures contract) would be expected the win • Then no one would volunteer to be on the other side of that bet • Consistency problem • If unbiased from one perspective, it must be biased in the other perspective, i.e., $/£ and £/$ • Known as the Siegel Paradox – not important in practice, however © 2018 Cambridge University Press 7-12 7.3 Risk Premiums in the Foreign Exchange Market • How much are you willing to pay for fire insurance? • If your home is worth $250,000 • Probability of a fire is 0.1% • $250,000 × 0.001 = $250 • Some are willing to pay more because they are risk averse • Analogous premiums in other areas to avoid uncertainty • Risk premium • What determines risk premium? • Expected return on the asset in excess of the risk-free rate • Modern portfolio theory posits that risk-averse investors like high expected returns but dislike a high variance © 2018 Cambridge University Press 7-13 7.3 Risk Premiums in the Foreign Exchange Market • Systematic risk • Risk associated with an asset’s return arising from the covariance of the return with the return on a large, well-diversified portfolio • Correlation: how two assets covary with each other [-1, 1] • The part of risk that commands a risk premium • Unsystematic (idiosyncratic) risk • Risk that is attributed to the individual asset and can be diversified away © 2018 Cambridge University Press 7-14 7.3 Risk Premiums in the Foreign Exchange Market • Capital Asset Pricing Model (CAPM) • Nobel Prize (1990) – William Sharpe • Determines an asset’s systematic risk • ( ) = + ( – ) • ( – ) is the premium • = ( , )/ ( ) © 2018 Cambridge University Press 7-15 7.3 Risk Premiums in the Foreign Exchange Market • Applying the CAPM to forward market returns • Since forward contract is an asset, there could be an associated risk premium • Dollar profits / losses can covary with the dollar return on the market portfolio • Can be viewed as risky and therefore deserving of premium • The other side would have to hold with knowledge that they expect a loss • i.e., like fire insurance, or in this case, portfolio insurance © 2018 Cambridge University Press 7-16 More on Risk Premiums in the Foreign Exchange Market • A general statement of the CAPM relationship for excess returns on asset j: Et{ R j( t+−+1) [1 it( , $ )} =β jt E{ R M( t +−+1) [1 it( , $ )} σ jM + + where β j = . σ jM is the covariance of Rt j ( 1 ) with RtM ( 1) σ MM σ MM is the variance of RtM ( +1) • Now we are interested in the excess return on a foreign investment St( +1) exrt( +=1) ×+( 1,£1,$it( )) −+( it( )) = R£ ( t +−+ 11,$) ( it( )) St( ) © 2018 Cambridge University Press 7-17 Risk premium continued • Applying the general formula, we have: Et exr( t+1) =βut E{ R M( t +−+1) [1 i( t , $ )} where Cov R( t++1,) R( t 1) β = tM£ j VartM R( t +1) • We will spend some time deriving this model soon! © 2018 Cambridge University Press 7-18 7.5 Empirical Evidence on the Unbiasedness Hypothesis • An econometric test of the unbiasedness hypothesis ,$/£ ( ,$/£) [ ,$/£ ( ,$/£)] , $/£ = = = [ + 30 , $/£] • ( ,$/£) ( ,$/£) − +30 − • fp (left-hand side variable) is the 30-day forward premium/discount • If hypothesis holds, the expected return to currency speculation will be exactly zero • Problem: Statisticians cannot observe how market participants form their expectations, so assumptions have to be made • Investors act rationally (no mistakes or bias) • Realized appreciation = Expected appreciation + Forecast error where error is news-induced (i.e., unexpected) • A test using the sample means • Weakest implication of unbiasedness hypothesis is that the unconditional mean of the realized appreciation is equal to the unconditional mean of the forward premium © 2018 Cambridge University Press 7-19 Exhibit 7.4 Means of Monthly Rates of Appreciation, Forward Premiums, and the Differences Between the Two © 2018 Cambridge University Press 7-20 Regression refresher . Suppose that our model has Yt as a function of only one variable, X1t : Yt=++ a bX11 tt U. Since cov(XUtt , )= 0 (we are assuming it is valid to estimate by a regression), then we have cov(YXtt ,11 )= b var( X 1t ) . This tells us that maybe one way we could estimate the parameter b1 is to take sample estimates of cov(YXtt ,1 ) and var(X1t ) (call these estimates

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